Fungal infections are a significant cause of morbidity and mortality in a variety of severely ill patients. For instance, fungi are able to cause superficial and often fatal disseminated infections in immunocompromised patients. Systemic fungal infections cause approximately 25% of infection-related deaths in leukaemics and 5-10% of deaths in patients undergoing lung, pancreas or liver transplantation. Acquired fungal sepsis is also known to occur in up to 13% of very low birth-weight infants.
Members of the Candida genus are responsible for most of the fungal infections in humans. They are the fourth most common cause of nosocomial bloodstream infections. However, other fungal species are also responsible for infections in humans. The members of the Aspergillus genus are the second most common cause of fungal infections behind the members of the Candida genus. However, other genera, including Malassezia, Trichosporon, Fusarium, Acremonium, Rhizopus, Mucor and Absidia, can be responsible for disseminated infections in humans.
The impact of a fungal infection is often exacerbated by a failure to rapidly diagnose and effectively treat the infection. Numerous studies have shown that a delay in appropriate therapy is associated with increased morbidity and mortality. At present, clinical methods of detecting the presence of a fungus in a patient are unreliable and time consuming. For instance, the detection of fungal infections is usually carried out by blood culture, which takes up to 1 to 2 days to perform and often provides false negative results. In addition, some fungi, such as members of the Pneumocystis genus, cannot be cultured easily.
The lack of rapid diagnostic tests for particular fungal species is one of the major impediments to successful management of infected patients. Different species of fungus, even in the same genus, vary in their susceptibilities to the common anti-fungal agents. Some species even display resistance to some agents. The identification of the specific fungal species causing an infection can be even more time consuming that simply detecting the presence of a fungus and this can often further delay effective treatment of the infection.
It is also important that various non-biological samples, such as surgical fluids and drinking water, are known to be fungus free. However, there is currently a lack of rapid tests for the presence of a fungus or for particular fungal genera or species in non-biological samples.